In vehicles such as automobiles, a vehicle-body structure is required that prevents vibrations that can occur in vehicle parts from being transmitted into a vehicle cabin as much as possible to improve ride comfort (sense of damped vibration) for occupants. To meet this requirement, the applicant has, in Patent Literature 1, proposed a technique that has an ingenious feature in the form of connecting a bulkhead (a reinforcing member) disposed within a frame that forms a closed cross-section to the frame. The connection form includes a rigid joint portion where the frame and the bulkhead are joined in a state of coming into contact with each other, and a flexible joint portion where the frame and the bulkhead are joined in a state of being disposed with a damper member therebetween.
In using a bulkhead including the rigid joint portion and the flexible joint portion in a closed cross-section portion, it is critical to effectively enhance vibration damping performance by means of a damper member. Unfortunately, depending on vehicle-body structures, distortion stress caused in association with vehicle vibrations cannot be concentrated on the damper member, failing to achieve a satisfactory vibration damping effect.